Springs under turntable

@lewm 

as is so often the case in this hobby, we have a phenomenon on one hand and a hypothesis on the other, and we marry them often without much evidence.

Shocker!  😎 

Added more of these things, now have them under the turntable, phono stage, amp, conditioner, and all 5 subs. Plus of course the different springs under the Moabs.

Things were going great until I started noticing a really bad drone or rumble. Immediately assumed it had to be the turntable, and spent a lot of time tweaking and adjusting making sure everything was perfectly level.

Thought I’d solved it a couple times but it kept coming back. Intermittent problems are the hardest! A couple times was sure it was solved, the record would play silent, but then comes the rumble. My big clue was playing Simon and Garfunkel Scarborough Fair, the lead-in groove would be nice and quiet at first until after several seconds the rumble would build up and be quite loud.

If it was the motor, or bearing, or anything like that it would be there every record all the time. This was telling me it had to be some kind of resonance in the system. I had been using springs under most of this stuff for quite a while with no problems until recently.

But now there were springs under the conditioner. Which is connected to a typically stiff power cord, also suspended. Which goes into the phono stage. Which is on springs. I remembered how much the low bass was affected by tuning the springs under the phono stage. Hmmm.....

Well if its a resonance then could be what’s happening is an inaudibly small amount of low frequency rumble is making its way through the system back to the phono stage where its creating a positive feedback loop and what I’m hearing is like that horrible mic feedback only instead of a shrieking scream its this low bass rumble.

Simple enough to check. Change the resonance, cancel the feedback, no more rumble. Wedged some stuff under one corner of the phono stage. Silence. Blissful silence.

I think what is going on is now with everything suspended everything moves more freely and for the most part this is good. Beyond good. Great! But it really is tuning, and a little care must be taken to avoid having too many things with the same resonance.

This will be highly system dependent. Look at my system. https://systems.audiogon.com/systems/8367 The conditioner is in a straight line between the sub amps and phono stage. The sub amps are one of the few things not suspended. Could be by springing the conditioner I unwittingly created a situation where the sub amps are feeding resonant energy right into the phono stage.

I don’t expect many to have this problem- at least not until they get to where a lot of the system is suspended. Main reason I mention it is because, if you think about it, the same could be happening a lot more often than we think- just at a much less obvious level and without the drone that made this so (relatively) easy to track down.

My turntable and monoblocs are on springs. When I added them to the phono-preamp, I lost bass response. Frequency response tilted up in the mids. No resonant drone or rumble. Replaced with metal cones and all returned to normal.

Just a suggestion, try the springs between the wood platform and the concrete block.

With springs its very important they be tuned to the mass of the component. What seems to work best is a spring soft enough to compress about half way when loaded. If it compresses more than 2/3 then the component is too heavy and you need to use more or stiffer springs. This is what I had with my phono stage at first, and it resulted in way too much deep bass and a somewhat rolled off top end. All I did was add a spring, making the whole suspension stiffer. This tightened up the bass a lot while at the same time improved top end extension.

Phono stages tend to be pretty light weight. I would bet your bass was lost because the phono stage was too light for the springs you were using. You could test this very easily by changing (removing) springs, or adding weight ala mahgister. He has played around and noticed even a change of a pound or two makes a difference in the response.

You have Nobsound, right? Did you try it with fewer springs? You may only need 2 springs per footer. I only need 3, and that’s for the Herron phono stage on BDR Shelf with another small Shelf on top plus one 2 lb dive weight! Once you get the number of springs right fine tune with weight on top of the component. I have a small bag with about 2 lbs of lead shot in it and the difference it makes with cones is barely noticeable but the difference on springs is obvious.

Right now my amp and phono stage are on BDR Shelf, with the springs under the Shelf. Need to try moving them to between the component and the Shelf. When I can find the time..... problem is my system sounds so good now I don’t want to tweak I just want to listen!